With 2 maps on same material i am not able to see and paint on 2nd map in texture mode
I added two textures to the material as shown in the following image.



Now you can switch between the textures using the Texture Paint mode Slots tab.  You'll notice that the Slots tab shows up in the tools tab for me.  You can make this happen by shift clicking on a blank area of a tab's working space to pin it so it always shows up regardless of what tab you are currently using.